Studies will be continued on the stimulation of catecholamine release by cultured bovine chromaffin cells in response to carbachol vs. ionophores. These processes will be compared with respect to kinetics of release, extracellular ionic requirements, and sensitivity to transport and metabolic inhibitors. Gruanule membranes will be labeled extracellularly during their fusion to the plasma membrane and their subsequent fate and possible reincorporation into new granules monitored by subcellular organelle fractionation and two dimensional electrophoretic resolution of component polypeptides. In another phase of this work, we have begun the differential solubilization of chromaffin granule membranes, i.e. ghosts, by chaotropic agents and detergents. The extracts will be characterized by two dimensional electrophoresis and attempts will be made to characterize various polypeptide fractions with regard to biological function.